Determining an angle of rotation of an object frequently takes place by measuring and integrating an angular velocity of the object. The angle of rotation may be an opening angle, for example, i.e., an angle of rotation with respect to a predetermined object position having a predetermined angular value for which the object is regarded as “closed.” This may be an opening angle of windows or doors, for example.
Such applications are of interest for so-called “smart homes,” for example, with the aid of which a user may monitor and/or control all relevant areas and objects within his/her home.
The angular velocity is generally measured with the aid of a rotation rate sensor (gyroscope). A more accurate determination of the angle of rotation generally requires a continuous measurement of the angular velocity, and imposes great demands on the stability of the angular velocity measurement. In particular, there are great demands on the stability with regard to systematic measuring errors of the rotation rate sensor, and on preferably short reaction times after waking up from a standby mode.
A method for determining an angle of rotation of an object is described in U.S. Pat. No. 7,349,567 B2. In the method, a sample image of the object in a certain position is provided.
Based on the sample image, projection sums are determined for a plurality of possible angular positions of the object. Projection sums are likewise computed for an image of the object in the angular position to be determined. The angular position whose projection sum most closely corresponds to the projection sum for the image of the object is determined for the object.